Solveeit Logo
Login

Question

Physics Question on laws of motion

A 600 kg600\, kg rocket is set for a vertical fring. If the exhaust speed is 1000 ms−11000 \,ms^{-1} the mass of the gas ejected per second to supply the thrust needed to overcome the weight of rocket is

A

117.6 kgs−1 117.6\, kgs^{-1}

B

58.6 kgs−1 58.6 \,kgs^{-1}

C

6 kgs−16\, kgs^{-1}

D

76.4 kgs−1 76.4\, kgs^{-1}

Answer

6 kgs−16\, kgs^{-1}

Explanation

Solution

Thrust is the force with which the rocket moves upward given by
F=udmdtF=u\frac{dm}{dt}
Thus mass of the gas ejected per second to supply the thrust needed to overcome the weight of the rocket is
dmdt=Fu=m×au\frac{dm}{dt}=\frac{F}{u}=\frac{m \times a}{u} or dmdt=600×101000\frac{dm}{dt}=\frac{600 \times 10}{1000}
=6 kgs−1=6\,kgs^{-1}